The use of object-oriented (OO) architecture knowledge such as patterns, heuristics, principles, refactorings and bad smells improve the quality of designs, as Garzás and Piattini (2005) state in their study; according to it, the application of those elements impact on the quality of an OO design and can serve as basis to establish some kind of software design improvement (SDI) method. But how can we measure the level of improvement? Is there a set of accepted internal attributes to measure the quality of a design? Furthermore, if such a set exists will it be possible to use a measurement model to guide the SDI in the same way software process improvement models (Humphrey, 1989; Paulk, Curtis, Chrissis, & Weber, 1993) are guided by process metrics (Fenton & Pfleeger, 1998)? Since (Chidamber & Kemerer, 1991) several OO metrics suites have been proposed to measure OO properties, such as encapsulation, cohesion, coupling and abstraction, both in designs and in code, in this chapter we review the literature to find out to which high level quality properties are mapped and if an OO design evaluation model has been formally proposed or even is possible.